Fix: Discard only invalid periods
Fix: Discard only invalid periods

Discard only invalid periods instead of all obsolete periods to support modification of previous periods

tvoli/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player